Influence of the shape of the computational domain on the simulation results in the FDTD

Generally speaking, it is assumed that the smaller the size of the FDTD (finite difference time domain) cell, the better the result will be. In this communication, we show that the shape of the computational domain can significantly influence the accuracy of the results in the FDTD simulation. Specifically, an improper choice for the domain shape can dramatically degrade the FDTD results even if we use a very fine mesh in the simulation. An electromagnetic interference (EMI) problem is used as an example to demonstrate the proper selection process.